The supramolecular self-assembled state of nonliving dissolved organic matter (DOM) in our water supply—plant and animal detritus, waste materials, and pollutants—is chemically fascinating. The practical analytical (measurement of DOM) and environmental (fouling of water treatment membranes and adsorbents, water-based sensing, the transport of organic matter through the microbial loop, and the fate and transport of environmental pollutants) implications of this concept are numerous. Non-living diagenetic (degraded and rearranged fulvic and humic acids), biogenic (extracellular hydrophilic acids, amino acids, proteins, sugars, polysaccharides, carbohydrates, lipids, nucleic acids, and viruses), and anthropogenic (pesticides, pharmaceuticals and personal care products (PPCPs), macro-, micro- and nanoplastics, per- and polyfluoroalkyl substances (PFAS), etc.) coexist in water. Our conceptual model for supramolecular aggregation of DOM proposes that metachemical (≤1 μm diameter) and physical (&gt;1 μm diameter) hydrogels form a hierarchical ‘supramolecular within supramolecular’ self-assembling architecture. This presentation focuses on the supramolecular structures of DOM which act as a protective mechanism for organic carbon in terrestrial and aquatic environments, and that the chemically intrinsic "resilient," "refractory," "recalcitrant" protection of DOM is a function of the supramolecular forms. Weak, moderate, and strong hydrogen (H) bonding contribute to the formation of the supramolecular hydrogels in addition to other concomitant intermolecular forces such as van der Waals forces, entanglement, metal bridging complexes, and the potential for covalent bonding between supermolecules. Of the organic chemicals comprising DOM, diagenetic materials are anticipated to provide the primary glue and perform a substantial role in the formation of strong H-bonds over a wide pH range (1 to 13). The chemical property that makes transformed diagenetic materials unique among other forms of DOM is the multiplicity of carboxylate, phenolate, and other functional groups available to participate in strong H-bonds. A modern understanding of the spectrum of H-bond strengths will be discussed.

Intrinsic supramolecular resilience of abiotic aqueous dissolved organic matter

ACS Fall 2021

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